The present invention relates to ultrasonic probes particularly for medical diagnostic purposes, and more particularly to ultrasonic probes which scan an ultrasonic beam by a mechanical means.
FIG. 1 shows a conventional mechanical sector-scanning type ultrasonic probe (hereafter referred to as "MSP"). A sub-rotary shaft 106 is rotatably supported at its ends in a frame 101. The sub-rotary shaft 106 is rotated by a motor 102 through motor shaft 103, and bevel gears 104, 105. The rotation of the sub-rotary shaft 106 is transmitted to a rotor shaft 108 through spur gears 107 and 109. The rotor shaft 108 rotates a rotor 110 having ultrasonic transducers 111 for mechanical scanning.
The amount of rotation of the motor 102 is detected by a rotary encoder 112 which controls a driving circuit 113 of the motor 102. Reference numeral 114 designates an oil seal.
In the conventional MSP, the interlocking between the bevel gears 104 and 105 is poor, so that the rotation of the motor 102 cannot be transmitted smoothly to the rotor 110, which causes deterioration of the picture quality of an object.
Furthermore, the bevel gears 104, 105 generate considerable driving noise when meshing. In addition to this, the bevel gears 104, 105 are expensive.
Moreover, the rotation of the sub-rotary shaft 105 cannot be transmitted smoothly to the rotor 110, because of eccentricity of the spur gears 107, 109. The spur gears 107, 109 also generate considerable driving noise when meshing.